fft_tool.h File Reference

#include "rwimg.h"

Functions
int	fft_1D_forward (Bimage *p)
int	fft_1D_backward (Bimage *p)
int	fft_2D_forward (Bimage *p)
int	fft_2D_backward (Bimage *p)
int	farfarig (Bimage *p, int ifl)
	With MIXRIG and SCRAMRIG fast Fourier transform a 2D image. More...
int	mixrig (Bimage *p, int ifl)
	With FARFARIG and SCRAMRIG fast Fourier transform a 2D image. More...
int	scramrig (Bimage *p)
	With FARFARIG and MIXRIG fast Fourier transform a 2D image. More...
int	abtori (Bimage *p)
	Changes direct Fourier transform representation. More...
int	ritoab (Bimage *p)
	Changes direct Fourier transform representation. More...
int	zeroes (Bimage *p)
int	rephase_orig (Bimage *p)
	Shifting the origin by half the complex image size. More...

Detailed Description

Author

P.L. Bellon, F. Cantele and S. Lanzavecchia Dip. Chimica Strutturale e Stereochimica Inorganica Via Venezian 21, 20133 Milano, Italy

Date

Created: 7 04 2003

Modified: 07 07 2005

Function Documentation

abtori()

int abtori

(

Bimage *

p

)

Changes direct Fourier transform representation.

Parameters

*p

image

Returns

int 0

This subroutine changes the way in which a direct transform 
is represented; from the conventional form Txryr, Txiyr,
Txryi, Txiyi (here called a,b,c,d ) it produces a new 
representation in which real and imaginary parts
are calculated, for the frequencies of the type f(Kx,Ky)
and f(Kx,-Ky) .      
Coefficients are addressed by pointers in this way:
pp1 --> real f(Kx,Ky)       pp2 --> imaginary f(Kx,Ky)
pp3 --> imaginary f(Kx,-Ky) pp4 --> real f(Kx,-Ky)

farfarig()

int farfarig	(	Bimage *	p,
		int	ifl
	)

With MIXRIG and SCRAMRIG fast Fourier transform a 2D image.

Parameters

*p	image
ifl	direction of transformation (-1 = direct / 1 = inverse)

Returns

int 0

fft_1D_backward()

int fft_1D_backward

(

Bimage *

p

)

fft_1D_forward()

int fft_1D_forward

(

Bimage *

p

)

fft_2D_backward()

int fft_2D_backward

(

Bimage *

p

)

fft_2D_forward()

int fft_2D_forward

(

Bimage *

p

)

mixrig()

int mixrig	(	Bimage *	p,
		int	ifl
	)

With FARFARIG and SCRAMRIG fast Fourier transform a 2D image.

Parameters

*p	image
ifl	direction of transformation (0 = direct / 1 = inverse)

Returns

int 0

rephase_orig()

int rephase_orig

(

Bimage *

p

)

Shifting the origin by half the complex image size.

Parameters

*p

image

Returns

int 0

Coefficients are addressed by pointers in this way:
pp1 --> real f(Kx,Ky)      pp2 --> imaginary f(Kx,-Ky)
pp3 --> imaginary f(Kx,Ky) pp4 --> real f(Kx,-Ky)

ritoab()

int ritoab

(

Bimage *

p

)

Changes direct Fourier transform representation.

Parameters

p

image

Returns

int 0

This subroutine changes the representation of the
direct transform: from real & imaginary parts to the 
conventional one; here a,b,c,d ,pointed by pp1,pp2,
pp3 and pp4, have the following meaning:
a=TXrYr    b=TXiYi    c=TXrYi    d=TXiYr
where TX(Y)r(i) means real (imaginary) part of the coefficients 
obtained by a direct transform computed along the X (Y) direction.
A quartet a,b,c,d is defined for each point of the reciprocal
space in the first quadrant (i.e. points with positive Kx & Ky
coordinates.     

scramrig()

int scramrig

(

Bimage *

p

)

With FARFARIG and MIXRIG fast Fourier transform a 2D image.

Parameters

*p

image

Returns

int 0

Rearrange each row in the complex image.

zeroes()

int zeroes

(

Bimage *

p

)

Parameters

*p

image

Returns

int 0